Roy Freeland, C.E.O.Roy Freeland, C.E.O. Perpetuum LtdPerpetuum LtdVibration Energy HarvestersVibration Energy Harvesters

Practical Alternatives for Successful Energy Harvesting

Alternative Methods of Powering Sensors

WirelessSensor power

supplies

PowercastMains

RF Induction

MainsHard Wired

Energy Harvest

Solar

Vibration

MicropeltHeatDiff

PerpetuumElectro - magnetic

Magneto - strictive

Electro - static

ManyPiezo - electric

TadiranBatteriesFuel Cells

EnoceanMotionOther Kinetic

Energy Harvesting Source Options• SolarSolar

– Widely used for power generationWidely used for power generation– Can be used for sensors e.g. Enocean in buildingsCan be used for sensors e.g. Enocean in buildings

• ThermalThermal– Requires temperature difference. Peltier effect devices Requires temperature difference. Peltier effect devices

can be used. Limited efficiency - Carnotcan be used. Limited efficiency - Carnot

• Wind/Wave/TidalWind/Wave/Tidal– Not normally practical as reliable source for sensorsNot normally practical as reliable source for sensors

• Machine vibration/motionMachine vibration/motion– When present is ideal source of energyWhen present is ideal source of energy

Vibration/motion energy harvesting• Converts movement of mechanical

resonator into electrical power:– Seismic mass should be as large as

possible.– Resonator should stay tuned near

vibration frequency.

• Power transduction mechanism should be:– Efficient– Reliable– Low cost– Compact

Power transduction mechanisms

• PiezoelectricPiezoelectric– Ceramic MaterialCeramic Material– SimpleSimple– Low-costLow-cost– CompactCompact– Long term reliability?Long term reliability?– High internal resistanceHigh internal resistance

• MagnetostrictiveMagnetostrictive– New materialsNew materials– Two-stage conversionTwo-stage conversion– Efficiency?Efficiency?– Immature technologyImmature technology– Reliability?Reliability?

• ElectromagneticElectromagnetic– Copper/steel/NdFeBCopper/steel/NdFeB– SimpleSimple– Low-costLow-cost– CompactCompact– ReliableReliable– Accurate ModelsAccurate Models

• ElectrostaticElectrostatic– Requires initial chargeRequires initial charge

Technology ConvergenceReduced Power for - Transmitters - Microprocessors - Sensors

Increased Microgenerator

Power

Wireless battery free

sensors

Sensor/wireless systems designed for battery power……Sensor/wireless systems designed for battery power……

………….but many customers will not accept batteries.but many customers will not accept batteries

What to use and Where

• Natural Sources (Wind/Solar/Hydro)– Most are impractical for wireless sensors– Solar possible in some locations – (not Alaska)

• Batteries– Reliability issues– Add to maintenance burden– Use in non critical, easy to access e.g. domestic

• Assessing Energy Harvesting– What energy is available– Is it reliable– Is there enough– Select transduction method

Early Adopter Applications for Energy Harvesting Wireless Sensors

• Boeing, Enocean, Powercast, Advanced Cerametrics and others presenting here

• Successful applications using Vibration Energy Harvesting

• Some details still commercially confidential as users wish to exploit competitive advantage

Condition Monitoring – Petrochemical

• Condition Monitoring System for major International Oil Co.

• Integrated with standard system from leading C.M Company

• Dust Networks radio

• ATEX Zone 1

• Transmits full vibration spectra

• Conventional Hard wiring too expensive

Condition Monitoring – Water Utility

• Yorkshire Water need to increase C.M. to reduce maintenance costs and improve service levels

• RLW Inc. developed W.S.N.– Moteiv radio – TI Chipcon2420 -802.15.4

• 6 kBytes vibration spectrumevery 10 minutes

• Pruftechnik Software

Wireless Microcontroller Module

Sensor IO Module

Power Management Module

Perpetuum PMG7Power Generator

Sensors -Accelerometer &Temperature(Behind Generator In Base)

S5NAP Assembly S5NAP Assembly

Pruftechnik VIBNODE RFA

Top cover

RF module

Perpetuum PMG17

Housing

PC board

Accelerometer

Mounting adapter

Temperature probe

•Launched at Hanover Fair April 2007

•2 Accelerometers per generator•Nanotron Radio

Practical Bandwidth and Stability

• Generator must cope with variations in:• Machine vibration frequency• Environmental temperature

• Narrow-band “hero” devices are of no practical use.

60Hz58Hz

Un-loadedmachinevibrationfrequency

Loadedmachinevibrationfrequency

VibrationFrequency

Highly-tuneddevice

Practicaldevice

Vehicular Applications

• Measured vibration of saloon car body• Power averaged over urban

driving including stops: 3mW

0 5 10 15 20 25 30 35 40 45 501 10 5

1 10 4

1 10 3

0.01

0.1Measured Vibration (Red) and Generator Response (Blue)

Vibration k

g2

Hz

Response k

kg

Hz

Frequency k

Hz

10 15 20 25 300.01

0.1

1

10Voltage spectrum

RMSVk 2

V2

Hz

freqk

Hz

Future Trends in Energy Harvesting

• Battery technology will improve but is not everlasting source

• Solar, Vibration and Thermoelectric most likely options for W.S.N.’s

• Vibration will provide main power source in Industrial and Transportation sensing

• Energy Harvesting is key to unleashing demand for benefits of wireless

Conclusion - Energy Harvesting

• It can be done and it is being done• Many wild claims out there• Many laboratory devices• Ask – where is it working and with what

energy source?• Success comes from realistic selection of

proven device